#include <iostream>

namespace A
{
    int a = 999;
    int add(int a, int b)
    {
        return a + b;
    }
    double add(double a, double b)
    {
        return a + b;
    }
}
namespace B
{
    char a = 'q';
    double add(int a, double b)
    {
        return a + b;
    }
    double add(double a, double b = 0.1)
    {
        return a + b;
    }
}
namespace C
{
    int a;
    int b;
    int c;
}
using namespace A;
using namespace std;
int main()
{
    cout << a << endl;
    cout << add(2, 3) << endl;
    cout << add(1.2, 3.3) << "A" << endl;
    cout << B::a << endl;
    cout << B::add(5, 3.3) << endl;
    cout << B::add(9.9) << endl;
    cout << "abc--" << C::a << C::b << C::c << endl;
}